1. Field of the Invention
This invention relates to a brushless motor, and more particularly to a brushless motor having seven or more armature windings.
2. Description of the Prior Art
An electric motor used in electronic computer systems or other precision instruments preferably has a large number (e.g. seven or more) of armature windings in order to obtain a constant rotational frequency (R.P.M.). Further, for such applications, brushless type motors are preferred over commutator type motors because the former has a longer life than the latter as well as being free from various problems inherent to the latter. For example, in communtator type motors, the commutator gradually wears down due to friction thereby producing brush dust which may cause various problems in the system which it is being used in. Although conventional brushless motors do away with the above mentioned drawbacks, brushless motors having a relatively large number of armature windings also have the disadvantage that they can develop very little starting torque.
This is because only a few of the armature windings can be simultaneously energized in conventional brushless motors as will be described in more detail hereinafter with reference made to the accompanying drawings.